This marks the first time that a decline was noted in the number of people with health insurance since the government started collecting insurance coverage data in 1987.

"This is a pretty dramatic development. It's not just a percentage drop but a drop in the actual number of people who had health insurance," said Deborah Chollet, senior fellow and health economist with Washington-based Mathematica Policy Research.

The number of insured people has been rising untill now. The first-time fall may now be another factor speeding up the increase in the ranks of the uninsured.

"It also points to the obvious need for health reform," Chollet said.

"Historically what we've seen during recessions and then job recovery is that when unemployed people find new jobs, more of the newly employed find jobs that don't offer health coverage," she said. "This may be happening now."

More uninsured. The percentage of people without health insurance increased to 16.7 percent, or 50.7 million in 2009 from 46.3 million in 2008.

Between 2008 and 2009, the number of people covered by private health insurance decreased to 194.5 million from 201.0 million. The number covered by employment-based health insurance also declined to 169.7 million from 176.3 million.

The number covered by government health insurance such as Medicare and Medicaid climbed to 93.2 million from from 87.4 million.

Anyone who hasn't had insurance coverage at any time during a full year is considered to be uninsured by the government. So people who lost their jobs and their health insurance aren't considered uninsured until they've been without insurance for a full year.